Explore the Universe

The Sun

The sun, the star that dominates the solar system, supports all life on Earth.
Age: About 4.5 billion years
Surface Area: 2,347,000,000,000 square miles
Composition: Mostly hydrogen and helium
Length of day: 25.38 Earth days
Surface temperature: About 10,000 degrees F

Mercury

The closest planet to the sun, Mercury has the shortest orbit: a mere 88 days.
Average Distance from the Sun: 36 million miles
Atmosphere: Carbon dioxide, nitrogen, argon
Surface temperature: -279/801 degrees F (min/max)
Length of day: 58.646 Earth days
Origin of name: Named after the messenger of the Roman gods.

Venus

The second closest planet to the sun, Venus is also called the 'morning star' and 'evening star.' 
Average Distance from the Sun: 67,237,910 miles
Atmosphere: Carbon dioxide, nitrogen
Surface temperature: 864 degrees F (average)
Length of day: 117 Earth days
Origin of name: Named after the Roman goddess of love and beauty.

Earth

The third planet from the sun, Earth is the only planet known to harbour life.
Average Distance from the Sun: 92,955,820 miles
Atmosphere: Nitrogen, Oxygen
Surface temperature: -126/136 degrees F (min/max)
Length of day: 24 hours
Origin of name: Erda, the Anglo-Saxon word for 'ground' or 'soil.' It is the only planet not named after a figure of Greek or Roman mythology.

Earth's Moon

The moon is the Earth's only natural satellite.  
Age: About 4.5 billion years
 Average Distance from the Earth: 238,855 miles
Atmosphere: No atmosphere
Surface temperature: -279/261 degrees F (min/max)
Length of day: 27.322 Earth days

Mars

Mars is sometimes called the 'Red Planet' for its red, iron-oxide rich soil. 
Average Distance from the Sun: 141,633,260 miles
Atmosphere: Carbon Dioxide, Nitrogen, Argon
Surface temperature: -125/23 degrees F (min/max)
Length of day: 1.026 Earth days
Origin of name: Named after the Roman god of war.

Phobos

Phobos is one of two natural satellite of Mars. The other is Deimos.
Phobos orbits about 9,377 km from the center of Mars
Composition: it is made of a material similar to carbonaceous chondrite.
Phobos' density is too low to be solid rock, however, and it is known to have significant porosity.
Origin of name: Named after the Greek God Phobos, which means fear, who is a son of Mars.

Deimos

Deimos is one of two natural satellite of Mars. The other is Phobos. It is the smaller and outer satellite.
Deimos, like Mars' other moon Phobos, has spectra, albedos and densities similar to those of a C or D-type asteroid.
There are only two geological features on Deimos. These craters are named Swift and Voltaire.
Origin of name: Named after a figure in Greek mythology, which represents dread.

Asteroid

Asteroids are rocky fragments left over from the birth of the solar system; most orbit the sun in a belt between Mars and Jupiter.  
Distance to sun: The asteroid Phaethon comes closest to the sun at 13.9 million miles.
Largest known asteroid: Ceres (estimated diameter 590 miles)
Number of asteroids in solar system: More than 1 million Total mass of asteroids: 
Less than the mass of the Moon, 7.3483 x 10^22 kg

Jupiter

Jupiter is the largest planet in the solar system. 
Average Distance from the Sun: 483,682,810 miles
Atmosphere: Hydrogen, helium
Surface temperature: -162 degrees F (average)
Length of day: 0.41354 Earth days
Origin of name: Named after the ruler of the Roman gods.

Io

Io is the innermost of the four Galilean moons of Jupiter.
With a diameter of 3642 kilometers, it is the fourth largest moon in the Solar System.
Origin of Name: Named after Io, a priestess of Hera, who became one of the lovers of Zeus.

Europa
Europa is the sixth moon of the planet Jupiter.
Europa was discovered in 1610 by Galileo Galilei.
It is the smallest of the four Galilean moons.
It is slightly smaller than the Earth's moon.
Origin of name: Named after a mythical Phoenician noblewoman, Europa, who was courted by Zeus and became the queen of Crete.

Saturn

Galileo was the first person to observe Saturn, the ringed planet. 
Average Distance from the Sun: 885,904,700 miles
Atmosphere: Hydrogen, helium
Surface temperature: -218 degrees F (average)
Length of day: 0.44401 Earth days 
Origin of name: Named after the Roman god of agriculture.

Titan

Titan also known as Saturn VI is the largest moon of Saturn.
It is the only moon known to have a dense atmosphere and the only object other than Earth for which clear evidence of stable bodies of surface liquid has been found.
Titan was the first known moon of Saturn, discovered in 1655 by the Dutch astronomer Christiaan Huygens.

Mimas

Mimas is a moon of Saturn.
Mimas is the smallest known astronomical body of the solar system, which has a near-spherical shape due to its self-gravitation.
Origin of Name: Named after Mimas, a son of Gaia in Greek mythology.

Dione
Dione is a moon of Saturn.
Dione is composed primarily of water ice.
It is the third densest of Saturn's moons.
Origin of name: Named after the titan Dione of Greek mythology.

Uranus

It takes Uranus, the seventh planet from the sun, 84 Earth years to make one orbit. 
Average Distance from the Sun: 1,783,939,400 miles
Atmosphere: Hydrogen, helium, methane Surface temperature: -323 degrees F (average)
Length of day: 0.7196 Earth days
Origin of name: Named after the Roman god who was the father of the Titans.

Neptune
Neptune, the eighth planet from the sun, is thought to be the windiest in the solar system. 
Average Distance from the Sun: 2,795,084,800 miles
Atmosphere: Hydrogen, helium, methane
Surface temperature: -330 degrees F (average)
Length of day: 0.67125 Earth days 
Origin of name: Named after the Roman god of the sea.

Pluto

Once considered the solar system's ninth planet, Pluto was downgraded to a dwarf planet in 2006. 
Average Distance from the Sun: 3,670,050,000 miles
Atmosphere: A layer of frozen methane, nitrogen and carbon monoxide temporarily forms a thin atmosphere when Pluto is close to the sun.
Surface temperature: -369 degrees F (average)
Length of day: 6.387 Earth days
Origin of name: Named after the Roman god of the underworld.

Comet Hale-Bopp

Comet Hale-Bopp set a record for visibility to the naked eye - 19 months. 
Composition: Ice, dust, gas
Last visible from Earth: 1997
Next visible from Earth: 4035
Origin of name: Named after its two discoverers, Alan Hale and Thomas Bopp, who found the comet simultaneously in 1995.

Comet Halley

Sightings of this most famous comet are believed to have been recorded as early as 240 B.C.  
Composition: Ice, dust, gas
Last visible from Earth: 1986
Next visible from Earth: 2061
Origin of name: Named after Edmund Halley, who in 1705 predicted the return of the comet in 1758.

Helix Nebula

The Helix Nebula, one of the closest planetary nebula to Earth, is the glowing gas around a dying, sun-like star. 
Distance from Earth: Between 450 and 700 light years Magnitude: 7.3
Nebula type: Planetary (so called because they superficially resemble planets through telescopes)
Diameter: About 2.5 light years
Origin of name: The nebula is coil-shaped, like a helix.

Orion Nebula

The Orion Nebula, a cloud of gas and dust located in the direction of the Orion constellation, is the brightest diffuse nebula in the sky. 
Distance from Earth: 1,500 light years 
Magnitude: 4 (can be seen with naked eye)
Nebula type: Diffuse (large structure with no outline and a cloudy appearance)
Diameter: About 30 light years
Origin of name: Named after the constellation, Orion. Orion was a great and handsome hunter in Greek mythology.

Proxima Centauri

Proxima Centauri is the nearest known star to the sun. 
Status: Red dwarf
Distance from Earth: About 25 trillion miles or 4.22 light years
Composition: Hydrogen, helium
Surface temperature: About 5,612 degrees F
Magnitude: 11 (10,000 times fainter than the sun)

Black Hole

A black hole is an extremely dense body with a gravitational field so strong that nothing can escape from its immediate vicinity. 
Formation: When a massive star runs out of fuel and collapses in on itself.
Location: Supermassive black holes most likely lie at the centre of most galaxies, including the Milky Way.
Detection: Observation of their powerful gravitational effects, like the bending of light. 
Example: GRO J1655-40, observed by the Rossi Explorer satellite
Origin of name: These 'holes' appear dark because electromagnetic radiation, including light, cannot escape from them.

Milky Way

The large, disk-shaped galaxy that includes our sun and solar system. 
Distance from the Sun: About 26,000 light years from the sun to the center of the Milky Way, near Sagittarius. 
Structure: Barred spiral galaxy
Diameter: About 160,000 light years
Neighborhood: Local Group, a small group of more than 40 galaxies, including Andromeda (M31)
Origin of Name: The name derives from its appearance as a faintly luminous band that stretches across earth's sky at night.

Andromeda (M31)

Andromeda, or M31, is the closest galaxy to the Milky Way.
Distance from the Sun: 2.5 million light years
Structure: Barred spiral galaxy
Diameter: About 250,000 light years
Neighborhood: Local group, a small group of more than 40 galaxies, including the Milky Way.
Origin of name: In Greek mythology, Andromeda was a young woman rescued by the sea and put into the sky by Athena. It is also known as M31, as it was number 31 on astronomer Charles Messier's list of celestial objects that were not comets.